Pelvic Discontinuity

Matthew P. Abdel

Key Concepts

Pelvic discontinuity is a separation of the ilium superiorly from the ischiopubic segment inferiorly (Figure 41.1).
When performing a revision total hip arthroplasty (THA) in such a cohort, there are 2 simultaneous goals:
- Gaining long-term acetabular component stability.
- Healing across the bony discontinuity or “unitization” of the pelvis by healing of the superior pelvis to the superior aspect of the cup-construct and the inferior pelvis to the inferior aspect of the cup-construct.
Preoperative imaging is essential and includes the following:
- Anteroposterior (AP) pelvic radiograph
- AP hip radiograph
- Cross-table hip radiograph
- False profile hip radiograph
- Judet radiographs including obturator oblique and iliac oblique views
- ± Computerized tomography (CT) scan with 3-dimensional (3D) reconstruction
Contemporary management options for chronic pelvic discontinuities include:
- Hemispherical acetabular component placement and open reduction and internal fixation (ORIF) with pelvic plating (Figure 41.2). This method works best for acute pelvic discontinuities and has a lower healing rate for chronic discontinuities with severe bone loss and is not commonly used currently.
- Cup-cage construct (Figure 41.3).
- Distraction method (Figure 41.4). This method “unitizes” the pelvis but usually does not lead to healing of the actual discontinuity fracture lines.
- Custom triflange implant (Figure 41.5). This method requires several weeks’ lead time for implant fabrication.

Sterile Instruments and Implants

Instruments

Routine revision hip retractors.
Routine hip instruments to remove preexisting uncemented or cemented acetabular components.
Two ball spikes.
Two vice grips.
Intraoperative fluoroscopy or imaging.

Implants

Cup-Cage Construct (Author’s Preferred Technique)

Highly porous acetabular components of various diameters (particularly sizes 60 mm or greater)

Highly porous acetabular augments (of various sizes)

Figure 41.1 ▪ Illustration of an AP view of the pelvis showing a left pelvic discontinuity where the ilium superiorly is separated from the ischium inferiorly. Of note, there are several indicators of a pelvic discontinuity, including the visible fracture line, obturator ring asymmetry, and medial migration of the inferior hemipelvis with disruption of Kohler line. (Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved.)

Figure 41.2 ▪ Illustration of a hemispherical acetabular component with posterior column compression plating, typically reserved for acute pelvic discontinuities with adequate bone quality and quantity. (Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved.)

Figure 41.3 ▪ Illustration of a cup-cage construct where the highly porous acetabular component is placed on host bone, supplemental screws are placed superiorly and inferiorly, and a supplemental cage is placed on top of the acetabular component spanning the ilium to the ischium. (Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved.)

Figure 41.4 ▪ Illustration of the distraction method where an acetabular component that is 6 to 8 mm larger than the last reamer is inserted, allowing the elastic recoil of the pelvis to provide a rigid initial capture. (Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved.)

Supplemental screws
Supplemental full-cage or half-cage
Metal-cutting burr
Allograft bone chips

Distraction Method

Highly porous acetabular components of various diameters (particularly sizes 60 mm or greater)
Highly porous acetabular augments (of various sizes)
Supplemental screws
Supplemental full or half cage
Metal-cutting burr
Allograft bone chips

Custom Triflange

Custom triflange trial (provided by manufacturer)
Real custom triflange component (provided by manufacturer)
Custom triflange screws (provided by manufacturer)

Hemispherical Acetabular Component and ORIF With Plating

Highly porous acetabular components of various diameters (particularly sizes 60 mm or greater)
3.5-mm reconstruction plate with 2 plate benders and compatible drill bits and screws
Large pointed bone reduction forceps

Positioning

Lateral decubitus position with access to entire femur in case an osteotomy is required for acetabular exposure.

Surgical Approaches

A posterior approach is preferred as it allows for excellent acetabular exposure (including the posterior column and ilium).
An anterolateral approach is also acceptable.

Preoperative Planning